Hard-surface cleaning compositions generally comprise one or more surfactants, and, optionally, one or more hygiene agents.
Typically, the surfactants used in such cleaning compositions are selected from anionic, nonionic, amphoteric and cationic surfactants. Nonionics are very commonly used due to their effectiveness on fatty soils and the ease with which their foaming can be controlled. Of these surfactants, nonionics are reported as showing low biocidal activity, whereas certain anionic, cationic and amphoteric surfactants show biocidal activity under specific conditions of, for example, pH and concentration. However, the biocidal activity of surfactants is, with a few notable exceptions low and it is commonplace to add a separate hygiene agent to compositions.
Typical hygiene agents include, strong acids, alkali's, phenolics, and oxidants such as peracids and hypohalites. These, of which a typical example is hypochlorite, are generally highly reactive species which exhibit this reactivity in terms of one or more of, short shelf life, toxic, corrosive and irritant properties. In general, these reactive components are required at relatively high levels in formulations. Other less chemically reactive hygiene agents, such as 2,4,4'-trichloro-2'-hydroxy diphenyl ether (available in the marketplace as IRGASAN [RTM]), are effective at relatively low concentrations but are more expensive than simpler species and may be specific as regards their spectrum of activity. Many organic acids, including benzoic, salicylic and sorbic are known as preservatives in cosmetics and some food products, but these preservatives generally show lower biocidal activity than the above-mentioned chemically reactive hygiene agents when used at the same level.
Similar compositions are known outside of the field of hard surface cleaning. For example, EP 0331489 (PARKE DAVIS PTY.) discloses a formulation for the treatment of acne which comprises a surfactant and a biocide. The examples illustrate the invention by reference to combinations of specific surfactants with specific biocides. DE 3518929 (Hans-Joachim Gobel) disclose a formulation for the treatment of dandruff which comprises a commercially available hair washing composition, which is identified, but whose composition is not given, and salicylic acid. RO 64162 (MIRAJ, 1974) discloses an anti-dandruff lotion which contains 10-30% wt ethanol, water, 0.5-3% wt salicyclic acid, 0.5-3% wt fatty acid alkoyl-betaine amide and 0.1-1% wt undecylenic acid monoethanolamide. It is believed that the salicyclic acid in such formulations is present as a keratolytic agent: causing dead skin tissue to be shed.
In hard surface cleaning it is often necessary to disinfect a surface. A `disinfectant` can be understood to be a hygiene agent which shows a 100,000 fold or better reduction in the number of viable microorganisms in a specified culture when used at a level of around 0.5 wt %. This is generally known as a `log 5 kill`. Of the organic acids mentioned above, salicylic acid is generally regarded as the most effective biocide against common bacteria, but it's activity falls far short of that required of a disinfectant at practical concentrations.
Some surfactants have been found to potentiate the effects of certain hygiene agents. DE 3619375 (Henkel) discloses that alkyl polyglycoside (APG) surfactants show a synergy with alcohols and organic acids as regards hygiene. The examples disclose compositions which comprise APG and organic acids including salicylic acid. These compositions are used at strongly acidic pH, generally below pH 3.
In addition to surfactants and hygiene agents it is known to incorporate polymers in hard surface cleaning compositions.
U.S. Pat. No. 3,679,592 (1972) discloses alkaline, cleaning and soil preventative compositions which comprise surfactant and 1-10% wt, particularly 4%, of a film forming component. GB 1528592 (1978) discloses alkaline, floor cleaning compositions. U.S. Pat. No. 4,252,665 (1979) discloses aqueous, alkaline, hard surface cleaning compositions of pH 9-12 which comprise a `detergency-boosting` acrylic copolymer having a molecular weight substantially in excess of 100,000 in combination with anionic surfactants.
U.S. Ser. No. 07/297,807, as described in EP 0467472 A2 (Colgate Palmolive) demonstrates that the incorporation of 2.3% of a 15-20% aqueous solution of the cationic polymer poly-[beta(methyl diethyl-ammonium) ethyl-methacrylate] in a mixed nonionic surfactant system for hard surface cleaning results in significant improvement of ease of subsequent re-cleaning of previously soiled and cleaned ceramic tiles. These cationic polymers are rather more expensive than commonplace acrylic and methacrylic polymers and some doubt has been cast upon the environmental acceptability of cationic species containing quaternary nitrogen.
U.S. Pat. No. 4,678,596 relates to a rinse aid formulation for HDW and MDW of pH 7.5-10 which comprises 5-60% nonionic surfactant (examples are 15%), preferably 2% wt of anionic poly(meth)acrylic acid polymer of molecular weight 1,000-50,000. The pH is limited by the stability of the composition (which is unstable at pH 7.0: see table 4 of citation).
U.S. Pat. No. 4,657,690 relates to a washing and foaming composition for hair and skin (pH range is 4.5-7.7) which comprises nonionic (around 5%) and poly(meth)acrylic acid (anionic polymer). The weight ratio of the anionic polymer to the nonionic surfactant is greater than 0.1:1, examples have 0.5-5% polymer and 0.5-7% nonionic with a lowest ratio of 0.2:1.
EP 0379256 (Colgate 1989) relates to stable acidic disinfectant liquid cleaning compositions which comprises, nonionic surfactants in a mixed system, organic acids, and an acid stable disinfectant of which quaternary nitrogen based materials are used in the examples. It is noted in the specification that a polymer can be present as a soil release agent.